Ultrastructural changes of the rabbit corneal epithelium and endothelium after Timoptic treatment.

The purpose of this study was to determine whether timolol maleate (Timoptic) is cytotoxic to the cornea. The drug was applied as topical drops for 1 month to control rabbit eyes and rabbit eyes from which the epithelium had been removed or to de-epithelialized full-thickness autografts. Clinically all corneas and grafts remained clear. Scanning and transmission electronmicroscopy however revealed is drug induced epithelial damage, defective epithelial wound healing, and endothelial changes. The endothelial changes were most prominent in the group of rabbits that underwent de-epithelialization before corneal grafting.